Method and device for producing a dry-laid fibrous web
The method and device address the energy-intensive wet process by reducing the co-carrying effect between rollers and the fiber fabric, enhancing process reliability and quality in fibrous web production.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- VOITH PATENT GMBH
- Filing Date
- 2025-11-03
- Publication Date
- 2026-06-11
AI Technical Summary
The existing wet process for producing fibrous webs, such as paper and cardboard, requires significant energy for drying due to the formation of hydrogen bonds, and there is a risk of the fiber fabric deviating from its intended path during the manufacturing process, leading to reduced process reliability and quality.
A method and device that reduces the co-carrying effect between rollers and the fiber fabric by guiding it through a press gap with reduced guiding effects, using release agents, vacuum, and controlled roller torques to ensure symmetrical detachment and prevent adhesion, thereby maintaining the fiber fabric's path and preventing wrapping or tearing.
The method and device enhance process reliability and quality by ensuring the fiber fabric follows its intended path without stretching or forming waves, maintaining strength and reducing energy consumption.
Smart Images
Figure EP2025081621_11062026_PF_FP_ABST
Abstract
Description
[0001] Method and apparatus for producing a dry-elasticated fibrous web
[0002] The invention relates to a method for producing a dried fibrous web, in particular a tissue, paper or cardboard web or a nonwoven web, comprising the following steps: a) raw material preparation of cellulose-containing fibers into individual fibers and / or fiber bundles; b) forming the individual fibers and / or fiber bundles in a fiber-air volume flow into a planar fiber layup, in particular on a forming belt by a dry forming process; c) application of a fluid, in particular water and / or a water-additive mixture, to the fiber layup in front of at least one press gap formed by two rollers; d) compacting the planar fiber layup to produce a fibrous web by applying pressure and / or temperature in at least one press gap.
[0003] Many fibrous webs, especially paper, cardboard, or tissue, were and still are produced almost exclusively using the wet process on an industrial scale. For this process, unless recycled paper is used, baled pulp is typically dissolved in large quantities of water in a vat, resulting in a fiber suspension consisting of approximately 99% water and only about 1% fiber by weight. This fiber suspension is then applied to a forming wire via a headbox to form sheets. The resulting fibrous web is subsequently dewatered or dried by pressure and heat until it can be wound up or otherwise processed. The wet process has the advantage that hydrogen bonds form between the individual fibers during dewatering or drying, giving the fibrous web the necessary strength.However, a disadvantage of this process is that drying the fiber web requires large amounts of energy. Especially in light of current climate change, there is therefore an intensive search for alternatives to this traditional wet process.
[0004] As an alternative to the wet process, the dry air-laying process is already known, in which fibers are laid down to form a fiber web in a largely dry state. To give the fiber web a certain degree of strength, small amounts of water (to form hydrogen bonds) and / or other binders are added. This results in significantly less energy being required for drying.
[0005] The embodiment shown in Figure 3 in publication WO 2019 / 137667 A1 already discloses a generic method, described above, for producing a dry-formed fiber web. In this process, fibers are first laid onto a forming belt to form a flat fiber mat using a dry forming process. The fiber mat is then transferred from the forming belt to a press belt. The press belt transports the fiber mat to a press gap formed by two rollers, through which the press belt and the fiber mat pass. The fiber mat is compressed in the press gap, thereby increasing its strength.
[0006] In the manufacturing process known from the prior art, there is a risk of the fiber fabric being carried along on the surface of at least one roller in the press gap as it exits the press gap, particularly due to a carrying effect developing within or originating from the press gap on the surface of at least one roller, which arises especially from the fiber fabric adhering to the surface. This can cause the fiber fabric to temporarily deviate from its intended path in the machine, for example, by forming a random wave shape and finding its way back to the intended path by following a press belt. Likewise, due to a carrying effect on the surface of a roller, the fiber fabric can permanently deviate from its intended path by wrapping around the roller or falling to the floor.Such a process-related disturbance, impairing the process reliability and / or the quality of the manufactured fiber web, or the deviation of the fiber layup from its intended course, is generally referred to as "sheet stealing".
[0007] It is therefore an object of the present invention to provide a method and a device for producing a dehydrated fibrous web, in particular a tissue web, with which the problems described above can be solved or at least reduced. In particular, it should make it possible to produce fibrous webs with increased process reliability compared to known manufacturing methods, preferably without reducing the quality, and especially without reducing the strength of the fibrous webs.
[0008] The problem described above is solved by the features of the independent claims. The dependent claims relate to advantageous embodiments of the present invention.
[0009] In particular, the problem is solved by a generic manufacturing process described above, which is characterized by the fact that a co-carrying effect between at least one roller of the at least one press gap and the fiber fabric is reduced in order to avoid the fiber fabric being carried along on a shell surface of the at least one roller when exiting the press gap.
[0010] Such a process, in which the raw material preparation is particularly low in water, has the particular advantage that the fiber web continues to follow its intended path after passing through the press gap and, in particular, does not adhere to the surface of a roller. Thus, the fiber web does not experience any stretching associated with being carried along the surface of a roller, nor does it form one or more waves, which can be unevenly distributed across the width of the fiber web, potentially impairing the quality and, in particular, the strength of the produced fiber web. Furthermore, wrapping around the roller, and especially tearing of the fiber web due to being carried along the roller surface, is prevented, so the proposed solution improves the process reliability of the manufacturing process.
[0011] In the proposed method, the fiber fabric is guided through a press gap formed by two rollers. As it passes through the press gap, the fiber fabric can be guided "unsupported," meaning directly against the outer surfaces of the two rollers. Alternatively, the fiber fabric can be guided against a web, such as a press screen or press web, and thus supported by it as it passes through the press gap. The other roller of the press gap is located on the side of the press screen or press web opposite the fiber fabric. In this way, as the fiber fabric passes through the press gap, it is guided on one side by the web, particularly the press screen or press web, and on the other side by the outer surface of a roller.
[0012] The guiding effect is therefore reduced in step e) such that, in a design where the fiber web is guided directly against the outer surfaces of the two rollers in the press gap as it passes through, both rollers exhibit the most equal (low) guiding effect possible. This allows the fiber web to detach evenly from both rollers and exit the press gap symmetrically with respect to the two rollers, i.e., without being affected by a particularly strong guiding effect on one of the rollers. Any adhesion of the fiber web occurs symmetrically on both outer surfaces, and thus on both sides of the fiber web, so that any adhesive force that might develop on both outer surfaces cancels itself out on both sides of the fiber web.
[0013] In a design where the fiber fabric is guided through the press gap by a web, in particular a press screen or press web, the guiding effect on the roller directly in contact with the fiber fabric is reduced in step e), so that this roller, or rather its outer surface, exhibits a lower guiding effect than the web supporting the fiber fabric. This allows the fiber fabric to continue being guided by the web, in particular a press screen or press web, during and after passing through the press gap, and ensures that only a lower guiding effect can develop on the outer surface of the roller in contact with the fiber fabric compared to the web, in order to prevent the fiber fabric from being carried along by the roller as it exits the press gap.
[0014] One or both of the rollers forming the press gap can be heated to apply a temperature in the press gap, particularly in addition to the pressing pressure, in order to improve the solidification effect by introducing heat energy into the press gap.
[0015] In one embodiment of the method, a release agent is applied to the fiber fabric and / or to the at least one roller in step e). This measure particularly utilizes the principle of reducing the adhesive force between the roller surface and the fiber fabric. To reduce the drag effect between the roller's surface and the fiber fabric, the fiber fabric can be treated. Specifically, the fiber fabric is treated with the release agent over its entire surface. "Over its entire surface" means that the release agent is applied substantially uniformly across the entire width or across the entire transverse direction CD of the fiber fabric.For example, a fluid applied to the fiber fabric can contain additives that reduce the surface tension of the fluid, especially water, thereby reducing any carry-along effect, particularly increased adhesion between the roller's surface and the fiber fabric, especially if caused by moisture. In this process, a vacuum can be applied to the fiber fabric on the side opposite the wetting side to draw ambient air through the fiber fabric and through a support element, such as a press belt, transfer belt, and / or drying screen, which is particularly permeable. This allows the penetration depth of the applied release agent into the fiber fabric and / or the quantity distribution in the machine direction (MD) or transverse direction (CD) to be influenced during the application of a release agent, particularly a liquid one.
[0016] Furthermore, the fiber fabric can be treated such that, before it passes through the press gap, a release agent, for example in particle form such as cellulose dust, is applied to at least one side of the fiber fabric facing a roller. Such a release agent is particularly suitable for reducing the drag effect between the at least one roller of the press gap and the fiber fabric, especially by preventing or reducing adhesion of the fiber fabric to the surface of the at least one roller as it exits the press gap.
[0017] To reduce the adhesion between the roller's surface and the fiber layup, the roller or its surface can also be treated or designed accordingly, particularly through a temporary or repeated measure such as applying a release agent, or through a long-term measure such as coating the surface or incorporating a surface structure that counteracts adhesion. For example, a metal coating, especially one containing chromium, or a hard metal thermal coating can reduce the surface tension of the roller's surface, thereby decreasing adhesion. Alternatively or additionally, the roller's surface can also have a surface structure that reduces adhesion and the resulting adhesion. Such surface structures are well-known, particularly in bionics.
[0018] Alternatively or additionally, the drag effect between the at least one roller and the fiber fabric can also be reduced by repeatedly applying a release agent, such as silicone, to the roller's surface. In particular, the drag effect between at least one roller and the fiber fabric can be avoided by combining a long-term and a temporary measure.
[0019] In one embodiment of the method, in step e), after the press gap, on the side of the fiber fabric opposite the roller, between which a co-traction effect exists, a vacuum is applied to the fiber fabric. This vacuum exerts a detachment force on the fiber fabric. The detachment force applied by the vacuum counteracts any co-traction effect caused, for example, by an adhesive force, and reduces it sufficiently to prevent the fiber fabric from being carried along the surface of the roller. In other words, the vacuum "sucks" the fiber fabric away from the roller. The vacuum is applied, in particular, immediately upon the fiber fabric's exit from the press gap, so that the co-traction effect can be reduced as soon as possible.
[0020] In one embodiment of the method, the fiber fabric is guided before and / or after the press gap at an angle α of 5° to 15°, particularly at an angle α of 10°, relative to the direction of the press gap. A guiding effect exists between the roller and the fiber fabric to increase the wrap angle β of the roller. The increased wrap angle also increases the distance over which the fiber fabric is guided on the roller's surface, resulting in a more continuous guidance of the fiber fabric and thus improving the uniform release of the fiber fabric from the roller's surface across its width.In particular, after exiting the press gap, the fiber fabric is guided for a certain distance along the roller's surface without the effect of pressure. This further promotes a uniform release of the fiber fabric from the roller's surface. Additionally, this extended guidance of the fiber fabric along the roller's surface also spatially improves the possibility of applying a vacuum to the fiber fabric on the side facing the roller.
[0021] In one embodiment of the method, the two rollers forming the press gap are driven with different torques in step e). Due to the different torques of the two rollers in the press gap, forces acting transversely to the pressing force can develop in the press gap, which can counteract the adhesion of the fiber fabric to the outer surface of a roller. This reduces the force required to detach the fiber fabric from the roller surface and thus lowers the tractive effect between at least one roller in the press gap and the fiber fabric.
[0022] In one embodiment of the method, in step e), a vibration with an ultrasonic frequency is applied to at least one roller. Vibrations with an ultrasonic frequency can also counteract the adhesion of the fiber fabric to the surface of a roller, particularly in the press gap, thus reducing the force required to detach the fiber fabric from the roller surface and lowering the co-traction effect between at least one roller in the press gap and the fiber fabric. In particular, a combination of rollers driven with different torques and vibrations in the ultrasonic frequency range applied to at least one of them has proven to be a suitable measure for reducing the co-traction effect, wherein the vibrations amplify the reduction of the co-traction effect by driving the two rollers with different torques.
[0023] In one embodiment of the method, in step e), the two rollers forming the press gap are subjected to opposite electrostatic charges. Due to the manufacturing process, the fiber fabric already possesses an electrostatic charge upon entering the press gap. By oppositely charging the two rollers forming the press gap, the fiber fabric is repelled by both rollers, thus reducing any co-guiding effect between the respective rollers and the fiber fabric on both rollers, or at least on one of the rollers, provided that the fiber fabric is guided directly on only one of the two rollers.
[0024] The present invention further relates to a device for producing a fibrous web, in particular a tissue, paper or cardboard web or a nonwoven web, comprising: a) a raw material preparation plant for the low-water processing of cellulose-containing fibers into individual fibers and / or fiber bundles; b) a dry forming device for the dry forming of the individual fibers and / or fiber bundles in an air stream to form a planar fiber layup on a forming belt; c) an application device for applying a fluid, in particular water and / or a water-additive mixture, to the fiber layup in front of at least one press gap formed by two rollers; and d) a consolidation device for consolidating the planar fiber layup by applying pressure and / or temperature in at least one press gap.The device is specifically designed to carry out the method according to at least one of the embodiments described above, and the solidification device has at least one guiding-lowering device to prevent the fiber fabric from being carried along on a surface of the shell of at least one roller when exiting the press gap.
[0025] The advantages and beneficial developments described above for the method according to the invention also apply analogously to the device according to the invention.
[0026] In one embodiment of the device, the follow-action lowering device is designed as a coating and / or as a structure and / or as a casing of the at least one roller. For the purposes of the invention, a casing differs from a coating or a structure in that the casing is formed in two parts with the roller, whereas the coating or a structure is formed in one part with the outer surface of the roller. A casing can, in particular, also be designed to be replaceable and, for example, may itself have a coating and / or a structure on its outer surface.
[0027] Coating the roller's surface or applying a structure to the surface that counteracts adhesion is a long-term measure that reduces the adhesion of the fiber layup to the roller's surface. For example, a metal coating, particularly one containing chromium, or a hard metal thermal coating can reduce the surface tension of the roller's surface, thereby decreasing the adhesion of the fiber layup. Alternatively or additionally, the roller's surface can also have a surface structure that reduces adhesion and thus the resulting adhesion effect. Such surface structures are well-known in the field of bionics.
[0028] In one embodiment of the device, the follow-action lowering device is designed as an application device for applying a release agent to the fiber fabric and / or to the at least one roller. Applying a release agent reduces the adhesive force between the roller surface and the fiber fabric. Such an application device extends, in particular, across the entire width of the fiber fabric.
[0029] The application device can be configured to apply a release agent, particularly a liquid or particulate one, to the surface of the roller and / or to the fiber fabric. For example, the application device can apply a release agent in the form of a fluid to the fiber fabric, containing additives that reduce the surface tension of the fluid, particularly water. This can reduce the tendency to stick, especially when caused by moisture, between the surface of the roller and the fiber fabric.
[0030] The application device is specifically designed to wet the fiber fabric with the fluid over its entire surface. "Overall surface" means that the release agent is applied essentially uniformly across the entire width or across the entire transverse direction (CD) of the fiber fabric. The application device can, for example, be a nozzle application device that applies the release agent to the fiber fabric in the form of a spray jet of individual small fluid droplets. Alternatively, the application device can be designed to apply the release agent in the form of foam, mist, or vapor.On the side of the fiber fabric opposite the wetting side, at least one vacuum box can be arranged, which, by means of a vacuum applied, particularly during application, can draw ambient air through the fiber fabric and through a support element supporting the fiber fabric, which is particularly permeable, for example, a press belt and / or a transfer belt and / or a drying screen. This makes it possible, in particular, to influence the penetration depth of the applied release agent into the fiber fabric and / or a quantity distribution in the machine direction MD or machine transverse direction CD during the application of a release agent, especially a liquid one.
[0031] The application device can further be configured to apply a particulate release agent, for example in the form of cellulose dust, to at least one side of the fiber fabric facing a roller before it passes through the press gap, particularly in a uniform layer as described above. Such a release agent is particularly suitable for reducing the drag effect between the at least one roller of the press gap and the fiber fabric, especially by preventing or reducing adhesion of the fiber fabric to the surface of the at least one roller as it exits the press gap.
[0032] This type of measure utilizes, in particular, the principle of reducing the adhesive force between the roller surface and the fiber fabric. Depending on the application, the application device can be designed to apply the release agent uniformly across the entire width of the fiber fabric or roller, or to apply a release agent only to specific areas of the fabric width, such as the edge region. An application device designed to apply a release agent to the fiber fabric is specifically designed for stationary, and especially continuous, operation, while an application device designed to apply a release agent to the outer surface of a roller is specifically designed for repeated and / or on-demand operation. Fluidic release agents, such as silicones or silicone oils, are more suitable for this application.In one embodiment of the device, on the side of the fiber fabric opposite the roller, between which and the fiber fabric the conveying effect is present, at least one vacuum means, for example in the form of a vacuum box or suction box as a conveying-effect lowering device, is arranged after the press gap, by means of which a vacuum can be applied to the fiber fabric.
[0033] The detachment force applied by the vacuum counteracts any dragging effect caused, for example, by adhesion, and reduces this effect sufficiently to prevent the fiber fabric from being dragged along the surface of the roller. In other words, the vacuum "sucks" the fiber fabric away from the surface of the roller. The at least one vacuum device, in particular a vacuum box, is typically designed, either individually or in series with other vacuum devices, in particular vacuum boxes, to apply a vacuum across the entire width of the fiber fabric.Furthermore, it is advantageous if the at least one vacuum means is designed and / or arranged in the device in such a way that a vacuum can be applied to the fiber fabric immediately upon its exit from the press gap, so that the conveying effect can be reduced as immediately as possible upon the exit of the fiber fabric from the press gap.
[0034] In one embodiment of the device, the fiber fabric is guided before and / or after the press gap at an angle α of 5° to 15°, particularly at an angle α of 10°, relative to the direction of the press gap, between the roller and the fiber fabric, where a guiding effect is present. The increased wrapping angle of the fiber fabric on the roller also increases the distance over which the fiber fabric is guided on the roller's surface. This, in particular, ensures continuity in the guidance of the fiber fabric, which improves the uniform release of the fiber fabric from the roller's surface across its width. Specifically, after exiting the press gap, the fiber fabric is guided for a certain distance on the roller's surface without the effect of any pressing pressure, which further promotes a uniform release of the fiber fabric from the roller's surface.Additionally, the extended guidance of the fiber fabric on the surface of the roller results in better spatial accessibility to the fiber fabric in order to apply negative pressure to the fiber fabric on the side of the fiber fabric opposite the roller.
[0035] In one embodiment of the device, the two rollers forming the press gap can be driven with different torques to create a follow-through / lowering effect. If the two rollers of the press gap are driven with different torques, forces acting transversely to the pressing force can develop in the press gap, which can counteract the adhesion of the fiber fabric to the outer surface of a roller. This reduces the force required to detach the fiber fabric from the roller surface and thus lowers the follow-through effect between at least one roller of the press gap and the fiber fabric.
[0036] In one embodiment of the device, the entrainment-reducing device is designed to apply a vibration with an ultrasonic frequency to the at least one roller. For this purpose, the roller itself or a bearing assembly of the roller can be operatively connected to a vibration unit, which applies the vibration to the roller and, in particular, to its outer surface in contact with the fiber fabric. Vibrations with an ultrasonic frequency, i.e., in the range of 20 kHz to 1 GHz, can counteract the adhesion of the fiber fabric to the outer surface of a roller, especially in the press gap, so that the force required to detach the fiber fabric from the roller surface is reduced and the entrainment effect between at least one roller in the press gap and the fiber fabric can be lowered.In one embodiment of the device, the conveying-effect-reducing device is designed to apply opposite electrostatic charges to the two rollers forming the press gap. For example, each of the two rollers forming the press gap is connected to a charge source to apply and, in particular, maintain a predetermined electrostatic charge on the respective roller. Since the fiber fabric already has an electrostatic charge from the manufacturing process upon entering the press gap, opposite charging of the two rollers forming the press gap causes the fiber fabric to be repelled by both rollers, thus reducing the conveying effect between the respective roller and the fiber fabric.
[0037] In the context of the present invention, the term "low-water" processing of cellulose-containing fibers into individual fibers and / or fiber bundles also includes processing the raw material entirely without the targeted addition of water and / or other liquids. "Low-water" raw material processing is understood to mean that the amount of water already contained in the provided, air-dried raw material is sufficient for the processing process, and the processing can be carried out without any further addition of water or moisture. The water content of the air-dried raw material is typically between 1% and 30%, particularly between 1% and 20%, and especially between 1% and 10%, based on the mass of the raw material.
[0038] Alternatively, in a "low-water" processing method, a small amount of water or moisture can be added to the raw material during the processing, so that the water content of the raw material, chips, and / or individual fibers does not exceed a maximum limit of 30%, in particular 20%, and in particular 10%, based on the mass of the raw material, chips, or individual fibers in the individual processing steps. It must be taken into account that the raw material can absorb water or moisture from its environment during storage for at least several hours, with this maximum amount depending on the raw material, the storage conditions, and the environmental conditions.
[0039] The invention expressly extends to embodiments which are not given by combinations of features from explicit cross-references of the claims, whereby the disclosed features of the invention can be combined arbitrarily with one another - insofar as this is technically sensible.
[0040] To differentiate between manufactured fiber webs, for example, a tissue, paper, or cardboard web on the one hand, and a nonwoven web (in English, "non-woven") on the other, the following distinction is made, which is based on fiber length, density, and fiber bonding type: A tissue, paper, or cardboard web is defined as a fiber web with predominantly medium fiber lengths, which are shorter than the fiber lengths of nonwoven webs, of less than or equal to 5 mm, in particular less than or equal to 4 mm, in particular less than or equal to 3 mm, predominantly bonded by hydrogen bonds, and with a bulk density of greater than or equal to 0.4 g / cm³. 3 Understood. The fibers used in a tissue, paper or cardboard web are additionally characterized by having a slenderness ratio (fiber length to fiber diameter) of less than or equal to 200, in particular less than or equal to 150, in particular less than or equal to 100.
[0041] A nonwoven web, which also consists primarily of fibers, is defined—as a key distinction from tissue, paper, or cardboard webs—by having a fiber content of at least 30% consisting of very long fibers with an average fiber length of more than 5 mm, or continuous fibers, which determine the nonwoven characteristics. Furthermore, a fiber-to-diameter ratio of greater than or equal to 300 is targeted for a nonwoven web. The remaining fiber content of a nonwoven web can be of a different composition, and the bulk density should be below 0.40 g / cm³. 3 to classify a fibrous web as a nonwoven fabric.
[0042] Further features and advantages of the invention will become apparent from the following description of a preferred embodiment with reference to the drawing.
[0043] The invention will be explained below with reference to the following figures.
[0044] Fig. 1 shows a schematic representation of an exemplary raw material processing plant for the particularly low-water processing of cellulose-containing fibers;
[0045] Fig. 2 shows a schematic representation of an exemplary fiber web plant for the production of a dry-formed fiber web;
[0046] Fig. 3 shows a schematic representation of another exemplary fiber web plant for the production of a dry-formed fiber web; and
[0047] Figs. 4a - 4f each show a schematic representation of a section of the fiber web system from Fig. 3 with two exemplary consolidation devices with at least one conveying-sinking device.
[0048] To clarify the individual directions, a higher-level Cartesian coordinate system is shown in the figures. The x-direction corresponds to a longitudinal extension, also referred to as the machine direction MD (Machine Direction). The y-direction corresponds to a direction orthogonal to the machine direction MD. It is also referred to as the machine cross-direction CD (Cross-Direction). The z-direction, on the other hand, corresponds to the vertical direction. Figures 1 to 3 each show a schematic representation of a possible embodiment of the method or device according to the invention. Figures 4a to 4f each show a schematic representation of a section of the fiber web system from Figure 3 with exemplary consolidation devices, including at least one feed-and-lower device.
[0049] Fig. 1 schematically depicts an exemplary embodiment of a particularly low-water processing plant, or low-water raw material processing plant 2, in which individual fibers and / or fiber bundles 209 can be produced, for example, from fiber-containing recycled material and / or from virgin fiber pulp as bales 200, by comminution devices 221, 222, 223 and / or fiberizing devices 222, 223. The individual fibers and / or fiber bundles 209 can be transported in an air stream after successful comminution or fiberizing. The air-fiber mixture can be fed via a distribution channel of the dry forming device 4 shown in Fig. 2 to a fiber web plant 3 for the production of a dry-formed fiber web 309.
[0050] A coupling of the two manufacturing processes of the low-water raw material preparation 2 and the fiber web plant 3 can be an important component for the production of high-quality fiber webs 309, both of which can be coordinated, controlled and / or regulated via a higher-level control and / or regulation device 60.
[0051] The exemplary low-water raw material processing process or raw material processing plant 2 can be characterized by a multi-stage comminution of the raw material, which is fed intermittently. At the end of the raw material processing process 2, an airflow containing dispersed individual fibers and / or fiber bundles 209, tailored to the subsequent fiber web plant 3, can be continuously provided. The raw material processing process or raw material processing plant 2 and the subsequent fiber web plant 3 are, in particular, free of any intermediate storage of the individual fibers 209 between plants 2 and 3 and can therefore be provided to the fiber web plant 3 "on demand".
[0052] The general term "raw material" is used for cellulose-containing fibers 200, in particular virgin fiber pulp as bales 200 and / or recycled fibers. The recycled fibers from the fiber web plant 3 can itself be high-quality recycled virgin fiber pulp and / or it may be planned that recycled material from waste paper is used to further improve the overall efficiency of the manufacturing process.
[0053] The raw material, which is supplied discontinuously, is typically fed as bales 200 via a conveyor belt 220 to a first shredding device 221. The first shredding device 221, in particular a first shredder 221, can be designed such that it can perform a first shredding of the bales 200 into coarse chips, shreds or chips 201.
[0054] The chips 201 can then be fed into a cleaning device 230, where any unwanted components, so-called "rejects," such as metals, contaminants, and / or packaging residues, that may still be contained in the chips 201 can be filtered out. In particular, after passing through the cleaning device 230, which can be, for example, a cyclone separator, the chips 201 are available as cleaned chips 202.
[0055] These cleaned chips 202 can ideally be temporarily stored in a larger storage unit 240, which can be designed as a silo. The storage unit 240 can be located immediately after the cleaning of the chips 201, keeping the increase in volume as small as possible. Optionally, a conditioning device 260 or a conditioning process can be provided for the cleaned chips 202 after the cleaning of the chips 201 and before the storage unit 240. During this conditioning process, a small amount of moisture can be added to the cleaned chips 202, for example, to minimize or prevent dust formation and / or electrostatic charging.
[0056] The storage unit 240 can be configured as a vertical storage silo 240, in which the cleaned chips 202 can be easily compressed by their own weight. Furthermore, at least one discharge device 241 can be provided in the storage unit 240, which enables continuous discharge of the cleaned chips 202. To assist the discharge of the cleaned chips 202 from the storage unit 240, an airflow can be introduced directly at the outlet of the storage unit 240, so that the cleaned chips 202 can be distributed and mixed in the airflow and thus transported to the second comminution device 222.
[0057] The second comminution device 222, or first fiberizing device 222, is, for example, designed as a first hammer mill 222, in which the cleaned chips 202 are comminuted or fiberized, in particular, until individual fibers with isolated nodes 205 are formed, which can then pass through a filter device included in the second comminution device 222. By supplying an airflow downstream of the second comminution device 222, the discharge of the individual fibers 205 from the second comminution device 222 can be supported, and the onward transport to the next processing station can be carried out. The individual fibers with isolated nodes 205B are, in particular, highly resolved in the supplied airflow.
[0058] The individual fibers with isolated nodes 205B can be further processed in a fiber processing device 250 to form a continuous mass flow of fibers 206, to which a further air flow can then be added and the continuous mass flow of fibers 206 becomes a particularly high-resolution, continuous mass flow of a fiber-air mixture 207.
[0059] The particularly high-resolution, continuous mass flow of a fiber-air mixture 207 can be fed directly to the third comminution device 223 or the second fiberizing device 223, which is particularly designed as a second hammer mill 223. The third comminution device 223 can comminute or fiberize the particularly high-resolution, continuous mass flow of a fiber-air mixture 207, in particular until essentially only individual fibers 208 remain, in particular free of knots or with only a small proportion of knots, which can then pass through a filter device arranged in the third comminution device 223.
[0060] To further reduce the concentration of individual fibers, another airflow can then be added. Alternatively or additionally, for example, exhaust air from the vacuum boxes 32 included in the fiber web system 3 can be added for web stabilization (see also Fig. 2) before the high-resolution individual fibers 209, essentially free of knots, can be precisely metered and continuously fed to the fiber web system 3 via a distribution system or distribution channels.
[0061] The fiber web system 3, schematically depicted in the embodiment shown in Figure 2, has a dry forming device 4. The fiber web system 3 could also have more than one dry forming device 4 in order to produce several superimposed layers of the finished fiber web 309.
[0062] The individual fibers and / or fiber bundles 209 transported by the airflow can be guided further to the dry forming device 4 and distributed as evenly as possible transversely to the machine direction MD or in the transverse direction CD of the fiber web system 3. Downstream of the dry forming device 4, at least one application device 7 can be provided, which can apply a fluid, in particular water or a water-additive mixture, to the fiber fabric 300 or the consolidated fiber fabric 305.
[0063] Furthermore, in the exemplary embodiment, at least one consolidation device 8 can be provided after the dry forming device 4, which can consolidate the fiber fabric 300. In the embodiment shown in Fig. 2, two consolidation devices 8 are arranged in the form of press gaps 83 and 81. In particular, at least one consolidation device 8 is designed such that it can, in addition to consolidating, also structure and / or heat the fiber fabric 300. The structuring by the consolidation device 8 can be used in particular for the production of a tissue web with low- and high-pressure zones, especially a tissue web with a basis weight of 28 g / m². 2 up to 42g / m² 2 be essential.
[0064] The dry forming step in the dry forming device 4 can be controlled and / or regulated by at least one included control and / or regulating means, wherein the individual fibers and / or fiber bundles 209 in the dry forming device 4 can be laid down, in particular partially, by the force of gravity onto a forming belt 40, which is in particular circulating and permeable, and can form a fiber fabric 300, which is in particular still substantially unconsolidated.
[0065] Furthermore, the dry forming device 4 can have at least one suction device 30 which supports the laying of the individual fibers 209 on the forming belt 40, and in particular can also influence it as a control and / or regulating means.
[0066] In particular, the mass distribution of the fiber layup 300 can be measured by at least one measuring device 61, in particular a mass measuring device extending in the machine transverse direction CD, wherein the measuring signal can act as a control variable, in particular via the higher-level control and / or regulating device 60, especially on the supply of the individual fibers without knots 209 from the raw material preparation plant 2 and / or on the suction device 30.
[0067] As shown in Fig. 2, the fiber fabric 300 deposited in the dry forming device 4 can pass through a first press gap 83 before the first application device 7, in which the still unconsolidated fiber fabric 300 can receive a first, full-surface pre-consolidation or pre-compacting over the entire transverse direction CD.
[0068] The application devices 7 can be designed as nozzle applicators which can spray a fluid in the form of a spray jet consisting of individual small fluid droplets onto the fiber fabric 300, 305. Alternatively, the application devices 7 can also be designed such that the fluid is applied in the form of foam, mist or vapor.
[0069] For example, the fibrous web 309 can be guided through a drying device 10, particularly an electrically operated one, immediately before being wound 12. The properties of the fibrous web 309 with regard to its thickness, its feel, and its absorption capacity can be advantageously maintained by means of a non-contact drying device 10. The non-contact drying device 10 can, for example, be designed as a hot air dryer, a flow-through drying hood, or a TAD dryer. Alternatively or additionally, the drying device 10 can also be designed with infrared elements.
[0070] Due to the small amounts of moisture used in the manufacturing process, the length of the dryer unit 10 can be kept very compact compared to the usual drying sections from wet lay-up processes. This allows the overall length of the fiber web system 3 and the associated infrastructure costs to be kept low.
[0071] The application devices 7 are designed such that the fiber fabric 300 can be wetted over its entire surface with the fluid. "Overall" means that the fluid is applied essentially uniformly over the entire width or over the entire transverse direction CD of the fiber fabric. In the application devices 7, a vacuum box 31 can be arranged on the side of the fiber fabric 300 opposite the side to be wetted. This vacuum box can draw ambient air through the fiber fabric 300 and through a support element, which is particularly permeable and supports the fiber fabric 300, by means of a vacuum applied, especially during application. This support element can be, for example, a pressure belt 41 and / or a drying screen 42. During the application of a fluid, this allows, for example, the penetration depth of the applied fluid into the fiber fabric 300 and / or the distribution of the fluid in the machine direction MD or the machine transverse direction CD to be controlled.It should be noted that the reference numeral 22 indicates the respective running direction of the press belt 41 and other coverings in Fig. 2.
[0072] Optionally, at least one moisture measuring device 63 and / or a measuring device for monitoring the fluid application may be provided. In particular, the at least one moisture measuring device 63 is arranged such that it can measure the moisture before and / or after the dryer device 10. It is also conceivable to provide a moisture measuring device 63 immediately after each application device 7. The moisture measuring device 63 can be stationary or traversing in the machine transverse direction CD. Furthermore, the moisture measuring device 63 can also be suitable for measuring other fiber web properties, such as mass, thickness, formation, opacity, or the like. After passing through the first press gap 83, the fiber layup 300 can be transported on the conveying run of the forming belt 40 to a transfer area.The transfer area serves to transfer the fiber fabric 300 from the forming belt 40 to the pressing belt 41. This transfer is particularly gentle, ensuring that even at high production speeds and with low moisture content of the fiber fabric 300, no impairment of its quality occurs.
[0073] The first press belt deflection roller is specifically vacuum-assisted to enable the "gentle" transfer of the fiber fabric 300 to begin immediately at the start of the transfer section. Several vacuum boxes 32 or other vacuum devices can be arranged in the screen loop of the press belt 41 behind the first press belt deflection roller to continue the transfer of the fiber fabric 300 over the entire length of the transfer section and to hold the fiber fabric upside down on the transporting section of the press belt 41 even after the transfer section has passed.
[0074] At the end of the conveying section of the press belt 41, the fiber fabric 300, which has been consolidated in particular by the second press gap 81, can be transferred from the press belt 41 to a drying screen 42 in a further transfer area. Although the fiber fabric 300 may exhibit a significantly greater strength after the second press gap 81 than before the second press gap 81, the principle of "gentle transfer" has also proven advantageous for the quality of the final fiber web 309 at this point.
[0075] In the area of the drying screen 42, a drying device 10 can be arranged in the fiber web system 3. The at least one drying device 10 can be located downstream of the application devices 72 and 73 to dry the fiber web 309 onto which the fluid has been applied. In particular, the at least one drying device 10 can be located upstream of a winding 12 of the finished fiber web 309 arranged in the fiber web system 3.
[0076] Fig. 3 shows a schematic representation of another exemplary fiber web plant 3 for producing a dry-formed fiber web 309, which differs in the design of the press belt 41 and the devices arranged in its area, as well as in the presence of an additional press gap 82 between the press belt 41 and the drying screen 42. In particular, the press belt 41 of the fiber web plant 3 of Fig. 3 is shorter, so that fewer vacuum boxes 32 are arranged in its area, especially downstream of the second press gap 81. In particular, an application device 72, arranged in the area of the press belt 41 in the fiber web plant 3 of Fig. 2, is located downstream of the press belt 41 and downstream of the additional press gap 82.
[0077] In the fiber web system 3 shown in Fig. 3, the fiber fabric 300, after passing through the second press gap 81, can be transported overhead on the conveying section of the press belt 41 to the transfer area, where the fiber fabric 300 can be transferred from the press belt 41 to the connecting belt 43. For this purpose, the press belt 41 and the connecting belt 43 are guided essentially parallel to a further displacement direction.
[0078] The connecting belt 42 allows the fiber fabric 300 to be guided from the press belt 41 to just before the third press gap 82, through which the fiber fabric 300 can then be guided unsupported. In the third press gap 82, the fiber fabric 300 can be further consolidated by pressure before it can be guided as a consolidated fiber fabric 305 to the dryer 10. The third press gap 82, like the second press gap 81, can be provided by the nip between two rollers. If the fiber fabric 300 is guided unsupported through the third press gap 82, unlike in the previous second press gap 81, no consideration needs to be given to the stability of a supporting fabric for the fiber fabric 300. Thus, it is possible to apply significantly higher pressures to the fiber fabric 300 in the third press gap 82 than is the case in the second press gap 81.The higher pressures allow for significantly greater strength in the finished 309 fiber web. The rollers should therefore be designed to be correspondingly robust. For example, the rollers can be made primarily of steel.
[0079] The connecting belt 43 is specifically designed to guide the fiber fabric 300 as close as possible to the third press gap 82, in order to keep the free pull, i.e., the distance that the fiber fabric 300 must travel unsupported between the connecting belt 43 and the third press gap 82, as short as possible. For this purpose, a final connecting belt deflection roller, i.e., the deflection roller at the end of the conveying section of the connecting belt 43, can have a relatively small diameter, and the connecting belt 43 itself can be sufficiently flexible to follow the correspondingly strong surface curvature of the final connecting belt deflection roller.
[0080] After leaving the third press gap 82, the consolidated fiber fabric 305 can be picked up in a transfer area by a transfer belt 44, which transfers the consolidated fiber fabric 305 to the drying screen 42. For similar reasons as before, the transfer belt 44 can be designed similarly to or identically with the connecting belt 43. In particular, the transfer belt 44 can be designed to pick up the fiber fabric 305 as close as possible to the third press gap 82 in order to keep the free pull, i.e., the distance that the further consolidated fiber fabric 305 must travel unsupported between the third press gap 82 and the transfer belt 44, as short as possible. For this purpose, the first deflection roller of the transfer belt 44, i.e.,The deflection roller at the beginning of the conveying section of the transfer belt 44 has a relatively small diameter, and the transfer belt 44 itself can be sufficiently flexible to follow the correspondingly strong surface curvature of this deflection roller. It should be noted that the press gap 83, after which the transfer belt 44 receives the fiber fabric 300, does not necessarily have to be a press gap 83 with free tension. It is also generally possible for the fiber fabric 300 to be guided through the press gap 83 with support.
[0081] To ensure the fiber fabric 300 can be guided as smoothly as possible, even at industrial production speeds, it is advantageous if at least one of the two rollers forming the third press gap 82 and / or the transfer belt 44 is / are adjustable in position such that the angle at which the compacted fiber fabric 305 exits the third press gap 82 can be precisely adjusted. For example, the two rollers forming the third press gap 82 can be designed to be adjustable in the z-direction. Alternatively or additionally, this roller arrangement could also be designed to be tiltable about an axis running in the machine transverse direction CD. In particular, it may also be possible to design the first deflection roller of the transfer belt 44 to be displaceable and / or pivotable in the z-direction and / or in the MD-direction.
[0082] Vacuum devices such as vacuum boxes or suction boxes, not shown in Fig. 3, can be provided in the sieve loop of the connecting belt 43 and / or in the sieve loop of the transfer belt 44. This applies particularly to the transfer belt 44, on which the further consolidated fiber fabric 305 can be transported hanging upside down. Here, the vacuum devices can help to hold the consolidated fiber fabric 305 against gravity on the transfer belt 44. Furthermore, vacuum devices in the sieve loop of the transfer belt 44 can be advantageous if a fluid is to be applied to the side of the further consolidated fiber fabric 305 facing away from the transfer belt 44. In order to protect the rollers that form the third press gap 82 between them from contamination or to keep the effort required for their cleaning as low as possible, it is advantageous if only water and / or dry strengthening agents are applied to the fiber fabric 300 in front of the third press gap 82.These result in no or only a minor, especially additional, co-traction effect between the roller and the fiber fabric, or in no or only minor soiling of the rollers. After the third press gap 82, however, a wet-strength agent can be applied to the consolidated fiber fabric 305, particularly by means of the application device 73, in order to impart a certain wet strength to the finished fiber web 309. Common wet-strength agents, in particular, tend to soil surfaces, at least until they have dried.
[0083] Furthermore, a cleaning device (not shown) may be provided which cleans the conveyor belt 44, in particular from contamination by applied liquids. A cleaning device may, for example, operate without contact using a medium such as compressed air or another gaseous or liquid cleaning medium. Such a cleaning device may, for example, be arranged within the screen loop of the conveyor belt 44.
[0084] Furthermore, vacuum boxes 31 arranged in the loop of the transfer belt 44 (not shown) can support a good hold of the overhead guided fiber fabric 305 on the transfer belt 44.
[0085] Figures 4a to 4f show schematic representations of a section of the fiber web system 3 from Fig. 3, each with exemplary consolidation devices 8, including at least one guiding-lowering device 100, 101, 102, 103, 104, 105, 106, which prevent the fiber layup 300 from being carried along a surface 810, 820 of the at least one roller 811, 821, 822 as it exits the press gap 81, 82. Figure 4a shows an exemplary consolidation device 8 in the form of a second press gap 81. In this process, the fiber fabric 300 is guided upside down through the press gap 81 formed by two rollers 811, 812, hanging from the press belt 41, with the upper side of the fiber fabric 300 contacting the press belt 41 and the lower side contacting the shell surface 810 of the roller 811.To prevent the fiber fabric 300 from being carried along on the shell surface 810 of the roller 811 when exiting the press gap 81, the roller 811 of the press gap 81 has a carrying-action-lowering device 100, which in the exemplary embodiment is designed as a coating 100 and / or structure 100 of the roller 811.
[0086] Figure 4a shows a further exemplary consolidation device 8 in the form of a third press gap 82. As described in more detail above with reference to Figure 3, the fiber fabric 300 is guided unsupported through the press gap 82 formed by two rollers 821, 822, with the upper and lower sides of the fiber fabric 300 each contacting a shell surface 820 of the rollers 821 and 822. To prevent the fiber fabric 300 from being carried along by one of the shell surfaces 820 of the rollers 821, 822 when exiting the press gap 82, the rollers 821, 822 of the press gap 82 have a guiding-lowering device 100, which in the exemplary embodiment is designed as a coating 100 and / or structure 100 of the roller 811.In at least one of the two rollers 821 , 822, the coating 100 and / or structure 100 is arranged on a casing 100 of the roller, so that it is replaceable, particularly in the event of wear of the carrying-action-lowering device 100.
[0087] Figure 4b shows another exemplary consolidation device 8 in the form of a second press gap 81. Here, too, the fiber fabric 300 is guided upside down through the press gap 81 formed by two rollers 811, 812, hanging from the press belt 41. The upper side of the fiber fabric 300 contacts the press belt 41, and the lower side contacts the outer surface 810 of the roller 811. To prevent the fiber fabric 300 from being carried along the outer surface 810 of the roller 811 when exiting the press gap 81, a groove is provided on the side of the fiber fabric 300 opposite the roller 811, between which and the fiber fabric 300 the carrying effect occurs.To prevent the fiber fabric 300 from being carried along, at least one vacuum means 102 is arranged after the press gap 81 as a suction-effect reduction device 102. This device applies a vacuum 101 to the fiber fabric 300 to prevent a suction effect between the fiber fabric 300 and the outer surface 810 of the roller 811. In other words, the vacuum 101 "suctions" the fiber fabric 300 away from the roller 811. A vacuum box 32 arranged before the fiber fabric 300 enters the press gap 81 serves to hold the fiber fabric 300 against the press belt 41 and does not contribute to preventing or reducing a suction effect between the fiber fabric 300 and the outer surface 810 of the roller 811.
[0088] Additionally, the exemplary press belt 41 shown in Fig. 4b is designed such that the fiber fabric 300 is guided at an angle α of approximately 15° to the roller 811 before and after the press gap 81, relative to the direction of the press gap 81. The following effect occurs between the roller 811 and the fiber fabric 300, in order to further reduce this effect by extending the guidance along the outer surface 810 of the roller 811 and, in particular, to create space for arranging the vacuum medium 102, especially as close as possible to the outlet of the press gap 81. The guidance of the fiber fabric 300 before and after the press gap 81 at an angle α of approximately 15° to the roller 811 relative to the direction of the press gap 81, resulting in a wrap angle β of approximately 30°, is shown more clearly in the detail shown in the lower right of Fig. 4b.
[0089] The embodiment of the section of the fiber web system 3 shown in Fig. 3 in Fig. 4c differs from the embodiment shown in Fig. 4b in that the fiber fabric 300 is guided towards the roller 811 at an angle α of approximately 15° relative to the direction of the press gap 81. This results in the fiber fabric 300 being guided for a shorter length of time on the outer surface 810 of the roller 811 compared to the embodiment in Fig. 4a, but also creates space for arranging the vacuum medium 102, particularly as close as possible to the exit point from the press gap 81.
[0090] Figure 4d shows another exemplary consolidation device 8 in the form of a second press gap 81. Here, too, the fiber fabric 300 is guided upside down through the press gap 81 formed by two rollers 811, 812, suspended from the press belt 41. The upper side of the fiber fabric 300 contacts the press belt 41, and the lower side contacts the outer surface 810 of the roller 811. To prevent the fiber fabric 300 from being carried along the outer surface 810 of the roller 811 as it exits the press gap 81, an application device 103 is arranged as a carrying-action lowering device 103 for applying a liquid release agent to the fiber fabric 300. For example, the application device 103 can apply a release agent in the form of a fluid to the fiber fabric 300, which contains additives that, for example, reduce the surface tension of the fluid, in particular water.This reduces the tendency to carry away material, particularly due to moisture, and especially increases adhesion between the surface 810 of the roller 811 and the fiber fabric 300. In particular, the application device 103 can also be integrated with an application device 71 for a fluid that is applied to the fiber fabric 300 in the press gap 81 to improve its consolidation. The fluid and the release agent can, for example, be applied separately to the fiber fabric 300. In another embodiment of the mechanism to reduce the tendency to carry away material, the release agent can also be added as an additional additive to the fluid applied to the fiber fabric 300 to consolidate it.
[0091] In addition, the fiber web system 3 shown in Fig. 4d also has a conveying-lowering device 104 (not shown in detail) in the form of an application device 104 for applying a particulate release agent, for example in the form of cellulose dust, to the shell surface 810 of the roller 811 in order to prevent the fiber fabric 300 from being carried along when exiting the press gap 81 on the shell surface 810 of the roller 811.
[0092] Figure 4e shows another exemplary consolidation device 8 in the form of a second press gap 81. Here, too, the fiber fabric 300 is guided upside down through the press gap 81 formed by two rollers 811, 812, hanging from the press belt 41. The upper side of the fiber fabric 300 contacts the press belt 41, and the lower side contacts the outer surface 810 of the roller 811. To prevent the fiber fabric 300 from being carried along the outer surface 810 of the roller 811 when exiting the press gap 81, a guiding and lowering device 105 is provided in the form of a drive unit 105, which drives the two rollers 811, 812 forming the press gap 81 with different torques.This allows forces acting transversely to the pressing force to form in the press gap 81, which counteract the adhesion of the fiber fabric 300 to the shell surface 80 of the roller 811 and thus reduce a co-carrying effect on the shell surface 810 of the roller 811 of the press gap 81 and the fiber fabric 300.
[0093] Additionally, the follow-action lowering device 105, in the form of the drive device 105, can also be configured to apply a vibration with an ultrasonic frequency to at least one of the rollers 811, 812, in particular by means of a flexurally coupled vibrating device which applies an ultrasonic vibration to the roller 811 and especially to its outer surface 810 that contacts the fiber fabric 300. Vibrations with an ultrasonic frequency can counteract the adhesion of the fiber fabric 300 to the outer surface 810 of a roller 811, particularly in the press gap 81, in order to reduce the force required to detach the fiber fabric 300 from the outer surface 810 and to reduce the follow-action between at least the roller 811 of the press gap 81 and the fiber fabric 300. Figure 4f shows a further exemplary consolidation device 8 in the form of a second press gap 81.Here too, the fiber fabric 300 is guided upside down on the press belt 41 through the press gap 81 formed by two rollers 811, 812, with the upper side of the fiber fabric 300 contacting the press belt 41 and the lower side contacting the shell surface 810 of the roller 811. To prevent the fiber fabric 300 from being carried along on the shell surface 810 of the roller 811 when exiting the press gap 81, a carrying-action-sinking device 106 is designed by applying opposite electrostatic charges to the two rollers 811, 812 forming the press gap 81, in particular by connecting each of the two rollers 811, 812 forming the press gap 81 to a charge source 106 in order to apply and maintain an opposite electrostatic charge on the respective roller 811, 812.Since the fiber fabric 300 already has an electrostatic charge from the manufacturing process when entering the press gap 81, if the two rollers forming the press gap 81 are charged in opposite directions, the fiber fabric 300 is repelled by both rollers 811, 812, thus reducing a co-traction effect between the roller 811 and the fiber fabric 300.
[0094] List of reference signs
[0095] 1 machine
[0096] 2 Raw material processing plant
[0097] 3 Fiber web plant
[0098] 4 T dry forming device
[0099] 7 Application device
[0100] 8 Solidification device
[0101] 10 T dryer device
[0102] 12 Roll-up
[0103] 22 Direction of travel
[0104] 30 Suction device of the dry forming device
[0105] 31 Vacuum box - Application device
[0106] 32 vacuum boxes
[0107] 39 extracted air
[0108] 40 Forming tape
[0109] 41 Press band
[0110] 42 Drying sieve
[0111] 43 Connecting strap
[0112] 44 Transfer belt
[0113] 60 Control and / or regulating device
[0114] 61 Measuring device
[0115] 63 Moisture measuring device
[0116] 71 first application device
[0117] 72 second application device
[0118] 73 third application device
[0119] 81 second press gap
[0120] 82 third press gap
[0121] 83 first press gap
[0122] 100 Coating / Structure / Sheathing of the jacket surface
[0123] 101 Vacuuming agents
[0124] Application device for a fluid
[0125] Application device for particles
[0126] drive unit
[0127] Charge source: cellulose-containing fibers (bales), shredded bales, chips, cleaned chips
[0128] Single fibers with isolated nodes or fiberized chips; Single fibers with isolated nodes or fiberized chips, high-resolution in a fiber-air mixture; continuous mass flow of fibers; continuous mass flow of fibers, high-resolution in a fiber-air mixture
[0129] Individual fibers essentially free of knots
[0130] single fibers and / or fiber bundles
[0131] Conveyor belt first shredding device second shredding device, preferably
[0132] Fibre-shredding device, in particular first hammer mill; third comminution device, preferably fibre-shredding device, in particular second hammer mill
[0133] Cleaning device
[0134] memory
[0135] Discharge device
[0136] Fiber processing device
[0137] Conditioning device
[0138] Fiber fabric solidified after dry forming device
[0139] Fiber web
[0140] Shell surface 811 roller
[0141] 812 roller
[0142] 820 mantle surface
[0143] 821 roller
[0144] 822 roller
[0145] MD Machine direction
[0146] CD machine transverse direction z vertical direction
Claims
- 38 - Patent claims 1. A method for producing a dried fibrous web (309), in particular a tissue, paper or board web or a nonwoven web, comprising the following steps: a) raw material preparation of cellulose-containing fibers (200) into individual fibers and / or fiber bundles (209); b) forming the individual fibers and / or fiber bundles (209) in a fiber-air volume flow into a planar fiber layup (300), in particular on a forming belt (40) by a dry forming process; c) application of a fluid, in particular water and / or a water-additive mixture, to the fiber layup (300) in front of at least one press gap (81, 82, 83) formed by two rollers (811, 812, 821, 822); d) Consolidating the planar fiber layup (300) to produce a fiber web (309) by applying pressure and / or temperature in at least one press gap (81 , 82, 83);e) Reducing the co-carrying effect between at least one roller (811, 812, 821, 822) of the at least one press gap (81, 82, 83) and the fiber fabric (300) in order to prevent the fiber fabric (300) from being carried along on a shell surface (810, 820) of the at least one roller (811, 812, 821, 822) when exiting the press gap (81, 82, 83).
2. Method for producing a fibrous web (309) according to claim 1 , characterized in that in step e) a release agent is applied to the fiber fabric (300) and / or to the at least one roller (811 , 812, 821 , 822). - 39 - 3. Method for producing a fibrous web (309) according to at least one of the preceding claims, characterized in that in step e) after the press gap (81 , 82, 83) on the side of the fiber fabric (300) which is opposite the roller (811 , 812, 821 , 822) between which and the fiber fabric (300) there is a co-feeding effect, a negative pressure (101 ) is applied to the fiber fabric (300) which exerts a release force on the fiber fabric (300).
4. Method for producing a fibrous web (309) according to at least one of the preceding claims, characterized in that the fiber fabric (300) is guided before and / or after the press gap (81 , 82, 83) relative to the direction of the press gap (81 , 82, 83) at an angle (a) of 5° to 15°, in particular at an angle (a) of 10° to the roller (81 1 , 812, 821 , 822), between which and the fiber fabric (300) a co-guiding effect is present in order to increase its wrapping angle (β) by the fiber fabric (300).
5. Method for producing a fibrous web (309) according to at least one of the preceding claims, characterized in that the two rollers (811 , 812, 821 , 822) forming the press gap (81 , 82, 83) are driven with different torques in step e).
6. Method for producing a fibrous web (309) according to at least one of the preceding claims, characterized in that a vibration with an ultrasonic frequency is applied to the at least one roller (811 , 812, 821 , 822) in step e). - 40 - 7. Method for producing a fibrous web (309) according to at least one of the preceding claims, characterized in that the two rollers (811 , 812, 821 , 822) forming the press gap (81 , 82, 83) are subjected to opposite electrostatic charges in step e).
8. Device (1) for producing a fibrous web (309), in particular a tissue, paper or cardboard web or a nonwoven web, comprising: a) a raw material preparation plant (2) for the low-water processing of cellulose-containing fibers (200) into individual fibers and / or fiber bundles (209); b) a dry forming device (4) for the dry forming of the individual fibers and / or fiber bundles (209) in an air stream into a planar fiber fabric (300) on a forming belt (40); c) an application device (71) for applying a fluid, in particular water and / or a water-additive mixture, to the fiber fabric (300) in front of at least one press gap (81, 82, 83) formed by two rollers (811, 812, 821, 822); d) a consolidation device (8) for consolidating the planar fiber fabric (300) by applying pressure and / or temperature in at least one press gap (81 , 82, 83);wherein the device (1) is designed in particular for carrying out the method according to at least one of the preceding claims, characterized in that the solidification device (8) has at least one carrying-action-lowering device (100, 101, 102, 103, 104, 105, 106) to prevent the fiber fabric (300) from being carried along on a shell surface (810, 820) of the at least one roller (811, 812, 821, 822) when exiting the press gap (81, 82, 83).
9. Device (1 ) for producing a fibrous web (309) according to claim 8, characterized in that the conveying-lowering device (100) is designed as a coating (100) and / or as a structure (100) and / or sheathing (100) of the at least one roller (811 , 812, 821 , 822).
10. Device (1 ) for producing a fibrous web (309) according to at least one of claims 8 or 9, characterized in that the conveying-lowering device (103, 104) is designed as an application device (103, 104) for applying a release agent to the fiber fabric (300) and / or to the at least one roller (811 , 812, 821 , 822).
11. Device (1 ) for producing a fibrous web (309) according to at least one of claims 8 to 10, characterized in that on the side of the fiber fabric (300) which is opposite the roller (811 , 812, 821 , 822) between which and the fiber fabric (300) the conveying effect is present, at least one vacuum means (102) is arranged after the press gap (81 , 82, 83) as a conveying effect lowering device (101 , 102) by means of which a vacuum (101 ) can be applied to the fiber fabric (300).
12. Device (1 ) for producing a fibrous web (309) according to claim 11 , characterized in that the fiber fabric (300) is guided before and / or after the press gap (81 , 82, 83) relative to the direction of the press gap (81 , 82, 83) at an angle (a) of 5° to 15°, in particular at an angle (a) of 10° to the roller (811 , 812, 821 , 822) between which and the fiber fabric (300) the following action is present.
13. Device (1 ) for producing a fibrous web (309) according to at least one of claims 8 to 12, characterized in that the driving-lowering device (105) is designed to drive the two rollers (811 , 812, 821 , 822) forming the press gap (81 , 82, 83) with different torques.
14. Device (1 ) for producing a fibrous web (309) according to claim 13, characterized in that the conveying-lowering device (105) is configured to apply a vibration with an ultrasonic frequency to the at least one roller (811 , 812, 821 , 822).
15. Device (1 ) for producing a fibrous web (309) according to at least one of claims 8 to 14, characterized in that the conveying-lowering device (106) is designed to impart electrostatic charges to the two rollers (811 , 812, 821 , 822) forming the press gap (81 , 82, 83) in opposite directions.